A variety of biometrically-based techniques for the identification of individuals have been proposed, many of which rely on iris recognition. Previous and existing patents in this field include the following: U.S. Pat. No. 4,641,349, Flom & Safir; U.S. Pat. No. 5,572,596, Wildes et al; U.S. Pat. No. 5,751,836, Wildes et al; U.S. Pat. No. 5,901,238, Matsushita; U.S. Pat. No. 5,956,122, Doster; U.S. Pat. No. 6,229,906, Pu & Psaltis; U.S. Pat. No. 6,247,813, Kim & Ryoo; U.S. Pat. No. 6,526,160, Ito; U.S. Pat. No. 5,291,560, Daugman; U.S. Pat. No. 7,650,520 Monro.
With conventional biometric recognition techniques, achieving a commercially acceptable False Acceptance Rate (FAR, where an individual is improperly identified as being known to the system) is in practice not too technically demanding. What is much more difficult, however, is achieving at the same time an acceptable False Rejection Rate (FRR, where a known individual is improperly rejected by the system). High false rejection rates in a commercial system are not conducive to easy consumer acceptance of the technology because of the anger and embarrassment that may easily be caused when a person who should be known to the system is incorrectly denied access. Generally however, the false acceptance and false rejection characteristics of a practical biometric system may not be as well separated as might be predicted from laboratory studies, because in the real world the quality of biometric data may not be ideal. Exactly the same considerations may apply to non biometric matching tasks. Although an embodiment of the invention is described in terms of specific biometric matching, in particular iris matching, the scope of the invention is not limited to any one kind of biometric image, nor is it limited to biometric images in general.